1. Field of the Invention
This invention relates to a photographic paper exposing method for printing images on photographic paper drawn out of a paper storage by irradiating the paper with light based on image data, and an optical digital printer employing this photographic paper exposing method.
2. Description of the Related Art
In an optical printer of the liquid crystal shutter type or the CRT type, a photosensitive material (which generally is photographic paper and will be referred to hereinafter as such or just as paper) must be positioned accurately in close contact with a beam emitting surface in time of exposure. A printer of the line exposure type, in particular, exposes photographic paper line after line while transporting the photographic paper. In order to print images with a condition to minimize a blank in a forward end region of elongate photographic paper, it is preferable to transport the photographic paper downstream of an irradiating point in an exposure unit once, and then expose the paper while drawing the paper backward.
However, the process of feeding the photographic paper downstream of the exposure unit and drawing the paper backward again to print each image thereon cannot promptly meet a demand for continuously printing a plurality of images on the photographic paper. In former times when digital printing was rare, one index print is added to prints in each order. Today, in an age of digital printing, a photo processing agent prints digital image data obtained from digital cameras and the like on photographic paper. The processing agent is required to process promptly a sudden order for a plurality of digital prints.
The object of this invention is to provide a technique for quickly printing a plurality of images, which is applicable to an optical digital printer for printing images on photographic paper drawn backward after being fed forward first.
The above object is fulfilled, according to this invention, by a photographic paper exposing method for printing images on photographic paper drawn out of a paper storage by irradiating the photographic paper with light based on image data, while drawing the photographic paper backward. This method comprises a first step, executed for printing a plurality of images on the photographic paper, of feeding the photographic paper by a length sufficient to print the plurality of images, past an irradiating point, a second step of successively printing the plurality of images on the photographic paper at the irradiating point while drawing the photographic paper backward, and a third step of feeding the photographic paper to a paper transport line extending to a developing unit.
With this method, the photographic paper is fed beforehand by a length corresponding to a number of prints to be made, and images are printed successively on the photographic paper as the paper is drawn backward. A plurality of prints are processed more quickly than where the photographic paper is reciprocated for making each print.
In a preferred embodiment of this invention, part of the photographic paper fed at the first step is shunted to a siding line branched from the paper transport line. With this method, even when the photographic paper is fed beforehand by a large length for a plurality of prints, the leading end of the photographic paper may be shunted to the siding line branched from the paper transport line. There occurs no inconvenience of the leading end of the paper moving toward the developing unit and entering a transport line in a cutter unit zone, for example, where a different transport mechanism is dominant. Further, a loop box may be provided for the siding line, the part of the photographic paper shunted to the siding line forming a loop in the loop box. Then, the photographic paper fed beforehand by a large length may be stored in a small space.
In a different preferred embodiment of this invention, the photographic paper on which the plurality of images have been printed at the second step is cut by a cutter unit disposed on the paper transport line, into individual prints to be transported to the developing unit. Thus, a length of photographic paper corresponding to a plurality of prints is never fed to the developing unit. The developing unit may retain an ordinary construction for processing cut paper.
Further, the foregoing object is fulfilled, in another aspect of this invention, by an optical digital printer comprising a transport mechanism for transporting photographic paper along a paper transport line extending from a paper storage to a developing unit, an exposure unit for printing images on the photographic paper transported backward toward the paper storage by the transport mechanism, by irradiating the photographic paper with light based on image data, and a siding line for shunting part of the photographic paper fed by a length sufficient to print the images in the exposure unit, the siding line being branched from the paper transport line downstream of the exposure unit.
With this construction, by utilizing the siding line, the photographic paper is fed beforehand by a length corresponding to a number of prints to be made, and images are printed successively on the photographic paper as the paper is drawn backward. A plurality of prints are processed more quickly than where the photographic paper is reciprocated for making each print.